Monday, May 1, 2023

Hibiscus: Plants with the most beautiful flowers

A scarlet rosemallow (Hibiscus coccineus):
 a Florida native

There are 432 Hibiscus species that are found worldwide, and with their beautiful flowers, many are grown in gardens and some are even used as crops. In general, the flowers are large and showy.

For example, see the scarlet rosemallow in the lead photo. Here there are five green sepals subtending five large red petals. The pistil, the female reproductive part of a plant, is attached to the center of the flower. The pistil is made up of a five-chambered ovary where seeds develop, the style that is a long tube between the ovary and five round stigmas where the pollen is absorbed. A stamen, the male reproductive structure, consists of the anther that holds the pollen, and a stalk called the filament. In hibiscus flowers, the filaments fuse into a tube that surrounds the style. Numerous anthers stick out from the filaments below the five stigmas at the top of the style. The prominent pistil with all those anthers is one reason the hibiscus flowers are so showy.

Nine hibiscus species are Florida natives, but there are also six nonnative species that have escaped cultivation. (See the Atlas of Florida Plants for the list.) There are also many more nonnative species being grown that have not escaped cultivation and have not been vouchered in the wild. The FNPS plants database includes seven of the native hibiscus species, which generally means that they are at least somewhat available in the native plant trade. 

Hibiscus is in the mallow family (Malvaceae). For more on the family and some of its useful members including cacao (chocolate) and the history of marshmallows, read my post on roselle.

Kew's worldwide range map for the 432 hibiscus species.

A favorite Florida native hibiscus

Scarlet rosemallow (Hibiscus coccineus), with its huge blooms (about nine inches across), is my favorite hibiscus and I'm not alone. It's marked as a favorite on the FNPS plant database. Years ago, when I regularly participated as a vendor at local garden-day plant sales events, I would always buy this plant to put next to my table for a couple of reasons: First, I knew I had a good place to plant it on the shoreline of the pond in our front yard. Secondly, it was a marketing decision because I knew people would stop and make some comment about the shape of the leaves. Third, it was one way to support the vendors who were selling native plants. One year, I bought a white one, which was striking, but it did not persist like the red ones, which are still going strong a decade later. 

Scarlet rosemallows need wet feet. A white Hibiscus coccineus

One year, when I was driving the back roads of Florida on a book tour, I stopped to take photos of this stand of scarlet rosemallows growing at the edge of a wetland next to the road. They were 15 feet tall and there were so many of them.

Scarlet rosemallows along a roadside in Central Florida were 15 feet tall!

Garden rosemallows

Garden rosemallows (Hibiscus rosa-sinensis var. rosa-sinensis) is native to Vanuatu, an island chain in the South Pacific west of Fiji and east-northeast of Australia, but is widely used as a tropical garden plant or a house plant around the world. Some botanists place the fringed rosemallow (Hibiscus rosa-sinensis var. schizopetalus), a scrambling shrub/vine, as a separate species, but the Atlas for Florida Plants considers it as a variety of the garden rosemallow. It's native to Kenya and Tanzania in eastern Africa. They are both widely planted in Florida.

There were several garden rosemallows in the landscape and planted in containers when we bought our house in 2004. Like most hibiscus, the petals are edible and I used them often in salads--I could select yellow, orange, or pink petals. The ones in the ground would die back after frosts in the winter, but they grew back in the spring for a few years, but eventually they all died.  

Garden rosemallow in a container on the back porch. A garden favorite: Hibiscus rosa-sinensis var. rosa-sinensis
I took these two photos (below) of the beautiful pink garden mallow flower and of the native scarlet rosemallow leaves on the same day in December. The native species had stopped blooming and was planning ahead for the winter by absorbing the chlorophyl and by losing its leaves in its preparation to die back, while the nonnative was partying like there's no tomorrow. It reminds me of the old Æsop fable of "The Ant & the Grasshopper."
Garden rosemallow in December in North Florida Scarlet rosemallow in December.

Hibiscus crops

There are two African hibiscus species that are grown as crops in Florida:
- Roselle (Hibiscus sabdariffa) has edible leaves, but the main crop is the calyx and epicalyx (the sepals) and not the fruit. They have an acidic taste and a burgundy color, which is surprisingly similar to cranberries and can be used instead of cranberries to make tea, sauce, and pies. 
- Cranberry hibiscus or false roselle (Hibiscus acetosella), which is grown for its sour leaves to use in salads and also to make tea. The epithet "acetosella" refers to sorrel and the sour taste. For more details read my article: Roselle: Florida's cranberry

As mentioned above, you can eat any of the hibiscus flowers, but some such as the roselle and the okra are too slimy to be appetizing raw, but they could be used in soups that may need some thickening.

While okra (Abelmoschus esculentus) is not a hibiscus, it is in the same family and the same subfamily: Malvoideae. It's a fast growing, heat-loving annual crop also native to Africa. When I grew burgundy okra, I was struck by how much it looked like the roselle--both the flower and the burgundy color of the stems and fruit. Read my post: Okra: a fast-growing, heat-loving crop.

Harvesting roselle where I'm holding three of the fruits. It's the outer layer, the calyx, that will become a pie or a sauce. I compost the fruit. This burgundy okra looks surprisingly similar to roselle--both the color and the flower.

Also in the mallow family...

Virginia saltmarsh mallow (Kosteletzkya pentacarpos) could be mistaken for a hibiscus because of its beautiful pink flowers. It occurs naturally on brackish or freshwater marshes through most of Florida and coastal areas as far north as New York and to the southern tip of Texas. The population in the photo is growing on the St. Johns River in Jacksonville where the river is an estuary and subjected to brackish tidal flows. 

So, add some native hibiscus to your landscape and try some roselle for an easy-to-grow crop. 

Green Gardening Matters,
Ginny Stibolt

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